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DR SARAH FIELDHOUSE PH.D. Fingerprint sampling devices; Methods for controlling fingerprint deposition.

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Presentation on theme: "DR SARAH FIELDHOUSE PH.D. Fingerprint sampling devices; Methods for controlling fingerprint deposition."— Presentation transcript:

1 DR SARAH FIELDHOUSE PH.D. Fingerprint sampling devices; Methods for controlling fingerprint deposition

2 Friction ridge skin identification Advancement of AFIS Latent mark detection Latent mark longevity Latent mark composition Latent mark development/ recovery techniques ‘fingerprint’ research Fingerprint research There are no universally accepted protocols for carrying out ‘fingerprint’ research. They all require ‘fingerprints’

3  asking participants to apply ‘moderate pressure’ [1]  asking participants to carry out specific tasks [2]  use of a top pan balance to apply a specified mass, which is then converted to force [4, 5]  use of a fingerprint sampler to control deposition [6] Examples of existing strategies to control fingermark deposition  researcher assisted deposition [3]

4 1. Variations in force application 2. Variations in contact time between the ridges and the substrate 3. Variations in contact area of friction ridge to surface contact Variations in fingermark deposition 4 inked fingerprints deposited by the same finger

5 145mm Deposition force management springs 110mm Finger resistor bar Deposition platform Adjustable finger clamp Finger Rest The fingerprint sampler The fingerprint sampler allows consistent and reproducible fingermark deposition, controlling physical factors associated with deposition [6].

6 Consistency in surface area Contact time controlled No distortion associated with mark deposition, e.g. force Improved ‘quality’ of marks compared to marks deposited without it’s use [6] Fingermarks deposited using the fingerprint sampler

7 There were two aims to this research project; 1.To develop a fingerprint sampler to facilitate fingermark deposition at different force quantities. 2.To study the effects of different force applications during latent fingermark deposition on the appearance of the resultant marks.

8 Adjustable base Finger rest 290mm 190mm Fingerprint deposition platform Force scale Direction of movement Fingerprint sampler 2 Multiple force capability

9 Fingerprint sampler 2 Spring Fingerprint deposition platform Finger rest 110mm

10 Hooke’s law of elasticity Spring calibration

11 Methodology 1. Latent and inked fingermarks were deposited from the same finger at approximate force quantities of 1N-10N at 1N increments onto glass surfaces and photocopier paper. For latent fingermarks participants were asked to refrain from washing their hands for 1 hour prior to deposition. The fingers were ‘loaded’ against an equivalent area of friction skin, i.e. a finger. 2. The latent fingermarks were then examined using Scanning Electron Microscopy. 3. The latent fingermarks were then developed using CNA fuming 4. Surface plot analysis commenced using a fingerprint digitiser (DCS121) 5. The inked fingerprints were examined for differences in surface area at different forces and consistency between marks at equivalent forces.

12 Results - Scanning Electron Microscopy 1N 5N 10N

13 Results - Surface plot analysis 1N3N 2N 4N

14 5N 6N 7N 8N

15 9N 10N 1N 5N 10N

16 Results - Differences in surface area Statistically significant differences were found to exist (N15, F72.485, p 0.00). Effect size large (0.838). Bonferroni post hoc tests suggest that these exist between the earlier force increments only. (p≤0.05).

17 Results - Differences in surface area Statistically significant differences were found to exist (N15, F99.622, p 0.00). Effect size large (0.877). Bonferroni post hoc tests suggest that these exist between the earlier force increments only. (p≤0.05).

18 Conclusions As the force applied to the finger increases; the quantity of friction ridge residue transferred to the resultant mark appears to increase, as does ridge depth. how the latent mark develops and how a mark is assessed. the surface area of the resultant mark increases (to a maximum point), especially important with marks deposited under less force. Differences in the quantity of force applied by friction ridge skin to a surface during mark deposition will affect the appearance of the resultant marks. This may affect; important for fingermark comparisons, e.g. how they change over time the consistency of samples in research projects

19 Implications for fingerprint research As part of a scientific approach to research it is important to recognise and control variables where possible. Fingerprint samplers represent a simple means of controlling physical variables associated with fingermark deposition. This approach might help to improve efficiency in the research approach. Fingerprint samplers can be useful teaching aids.

20 Further information Dr Sarah Fieldhouse (Staffordshire University), telephone: Philip Morton (SciChem), telephone: Thank you for listening, any questions?

21 References [1] Bohanan, A. M. (1998). Latent’s from Pre-pubescent Children Versus Latent’s from Adults. Journal of Forensic Identification. 48(5) p [2] Given, B. W. (1976). Latent Fingerprints on Cartridges and Expended Cartridge Cases. Journal of Forensic Sciences. 21(3) p [3] Croxton, R. Baron, M. Butler, D., Kent, T., Sears, V. (2010). Variation in amino acid and lipid composition of latent fingerprints. Forensic Science International. 199(1-3 p [4] Fieldhouse SJ. (2009) Consistency and reproducibility in the deposition and evaluation of latent fingermarks, contributing to an investigation into the effectiveness of a portable cyanoacrylate fuming system and aluminium powder for latent fingermark development (A thesis submitted in partial fulfilment of the requirement of Staffordshire University for the degree of Doctor of Philosophy). Stoke on Trent: Staffordshire University. [5] Jasuja, P., Toofany, M. A., Singh, G., Sodhi, G. S. (2009). Dynamics of latent fingerprints: The effect of physical factors on quality of ninhydrin developed prints – A preliminary study. Science and Justice. 49(8). [6] Fieldhouse, S., Consistency and reproducibility in fingermark deposition. Forensic Science International. 207(1-3) p


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